In the aforementioned applications, small gene-regulatory peptides are described that are present naturally in pregnant women and are derived from proteolytic breakdown of placental gonadotropins such as human chorionic gonadotropin (hCG) produced during pregnancy. These peptides (in their active state often only at about 4 to 6 amino acids long) were shown to have unsurpassed immunological activity that they exert by regulating expression of genes encoding inflammatory mediators such as cytokines. Surprisingly, it was found that breakdown of hCG provides a cascade of peptides that helps maintain a pregnant woman's immunological homeostasis. These peptides are nature's own substances that balance the immune system to assure that the mother stays immunologically sound while her fetus does not get prematurely rejected during pregnancy but instead is safely carried until its time of birth.
Where it was generally thought that the smallest breakdown products of proteins have no specific biological function on their own (except to serve as antigen for the immune system), it now emerges that the body, in fact, routinely utilizes the normal process of proteolytic breakdown of the proteins it produces to generate important gene-regulatory compounds, short peptides that control the expression of the body's own genes. Apparently, the body uses a gene-control system ruled by small, broken-down products of the exact proteins that are encoded by its own genes.
It is known that, during pregnancy, the maternal system introduces a status of temporary immunomodulation which results in suppression of maternal rejection responses directed against the fetus. Paradoxically, during pregnancy, often the mother's resistance to infection is increased and she is found to be better protected against the clinical symptoms of various autoimmune diseases such as rheumatism and multiple sclerosis. The protection of the fetus thus cannot be interpreted as only a result of immune suppression. Each of the above three applications has provided insights by which the immunological balance between protection of the mother and protection of the fetus can be understood.
It was shown that certain short breakdown products of hCG (i.e., short peptides which can easily be synthesized, if needed modified, and used as a pharmaceutical composition) exert a major regulatory activity on pro- or anti-inflammatory cytokine cascades that are governed by a family of crucial transcription factors, the NF-κB family, which stands central in regulating the expression of genes that shape the body's immune response.
Most of the hCG produced during pregnancy is produced by cells of the placenta, the exact organ where cells and tissues of mother and child most intensely meet and where immunomodulation is most needed to fight off rejection. Being produced locally, the gene-regulatory peptides which are broken down from hCG in the placenta immediately balance the pro- or anti-inflammatory cytokine cascades found in the no-man's land between mother and child. Being produced by the typical placental cell, the trophoblast, the peptides traverse extracellular space, enter cells of the immune system and exert their immunomodulatory activity by modulating NF-κB-mediated expression of cytokine genes, thereby keeping the immunological responses in the placenta at bay.